Fatty liver refers to a state where fat has excessively accumulated in liver (hepatocyte). With fat accumulation, various symptoms such as anorexia, weight loss, and fatigue appear. The mechanism of fatty liver development remains unknown, but the mechanism has been considered to be as follows on the basis of previous researches. In other words, the liver serves a crucial role in the metabolism and transfer of fat and fat balance in the liver is maintained at a constant equilibrium state in normal conditions. Liver neutral fat is derived from fatty acids in chylomicron from meal, free fatty acids mobilized from peripheral fat tissues, and fatty acids freshly synthesized in the liver. One part of fatty acids, which were thus freshly synthesized in the liver or transferred to the liver, is subject to oxidative destruction in the liver. Another part of fatty acids is esterified in a liver microsome and converted to a neutral fat. The neutral fat is bound to protein and secreted into bloodstream in a form of lipoprotein. Liver neutral fat is maintained at an equilibrium state with metabolic turnover in a relatively rapid manner. However, if changes occur, which disturb the equilibrium in the liver, that is, cause the disequilibrium between the production and utilization amounts of neutral fat in the liver, fatty liver develops. In theory, the causes of fatty liver are considered as follows: increased fat synthesis in the liver; decreased fatty acid oxidation in the liver; increased fat mobilization from deposit fat to the liver; and decreased fat transfer from the liver to the peripheral. As the causes of those abnormalities, there are given a number of causes such as: oxygen deficiency due to anemia gravis, circulatory disorder, etc.; endocrinopathy due to Graves' disease, etc.; metabolic disease due to child constitution, etc.; pancreatic disease; malnutrition; exogenous toxic agents or chemicals due to alcohol, phosphorus, mushroom poison, etc.; endogenous toxic agents due to chronic infection, etc.; fat and carbohydrate meal property; and small intestine bypass surgery. Fatty liver has been also considered as a factor of severe diseases such as chronic hepatitis and liver cirrhosis, and hence the treatment and prevention of the fatty liver has been a critical issue.
With respect to a method of preventing and treating fatty liver, for example, the following technologies have been known: a liver fat accumulation inhibitory composition characterized by containing an effective amount of conjugated diene linoleic acids together with a carrier for medicinal preparations or foods (for example, Patent Document 1); a fat and oil composition characterized by mixing fat and oil containing highly unsaturated fatty acids with egg yolk lipid containing about 25 to about 70% by weight of phospholipid (for example, Patent Document 2); a composition containing at least one kind of amino acids having a glucagon secreting activity, at least one kind of xanthine derivatives, and at least one kind of thiamine compounds (for example, Patent Document 3); a fraction of crude soybean lecithin having a function to suppress synthesis of neutral fat in liver, obtained by fractionating a crude soybean lecithin produced in the production process of fat and oil from soybean using organic solvents, adsorbents, ion-exchange resins, and the like, and a beverage/food, an animal feed, or a pharmaceutical agent obtained by mixing a known raw material with the crude soybean lecithin fraction (for example, Patent Document 4); a lipid metabolism improving agent and a hepatic disorder suppressing agent containing an extract of Phyllanthus niruri extracted with organic solvents or water as an active ingredient (for example, Patent Document 5); an agent for suppressing lipid increase containing xyloglucan as an active ingredient (for example, Patent Document 6); a composition, migrating from buckwheat flour to a liquid layer and separated in a mixture of the buckwheat flour and water (for example, Patent Document 7); an improver for lipid metabolism containing α-curcumene which is a bisabolane-type sesquiterpenoid isolated from Curcuma xanthorrhiza Roxb. as an active ingredient (for example, Patent Document 8); a fatty liver suppressing agent containing one or two or more kinds of triglycerides selected from tristearin, 1-stearyldipalmitin, 2-stearyldipalmitin, 1-palmitodistearin, and 2-palmitodistearin as an active ingredient (for example, Patent Document 9); an improver for liver function containing docosahexaenoic acid (referred to as DHA) as an active ingredient (for example, Patent Document 10); and an alcoholic fat liver suppresser containing hemicellulose obtained by removing starch, protein, and the like from corn wheat bran and extracting the residual part with an alkali and/or partially decomposed product of hemicellulose obtained by further treating the hemicellulose with xylanase as an active ingredient (for example, Patent Document 11). However, an effective method for prevention and treatment of fatty liver has not been established yet, a novel active ingredient with safety and high effectiveness and a composition containing the ingredient, and further a novel food and pharmaceutical agent using the ingredient and the composition have been desired.
For Lactobacillus gasseri which is a lactic acid bacterium, for example, the findings on the following have been obtained: an immunopotentiating agent (for example, Patent Document 12); an agent for preventing infection with pathogen (for example, Patent Document 13); an agent for preventing serum cholesterol level from increasing (for example, Patent Document 14); an antioxidant (for example, Patent Document 15); an agent for prevention, improvement, and treatment of diabetic complication (for example, Patent Document 16); and a medicine for preventing and treating inflammatory intestinal disease and allergic intestinal syndrome (for example, Patent Document 17). Patents for Lactobacillus gasseri have been published, but its influences on liver function and tissue characteristics have not been known at all.    Patent Document 1: JP 11-79987 A    Patent Document 2: JP 10-237480 A    Patent Document 3: JP 10-158170 A    Patent Document 4: JP 10-84879 A    Patent Document 5: JP 9-241176 A    Patent Document 6: JP 9-224608 A    Patent Document 7: JP 9-183735 A    Patent Document 8: JP 7-149628 A    Patent Document 9: JP 6-279278 A    Patent Document 10: JP 5-339154 A    Patent Document 11: JP 5-43470 A    Patent Document 12: JP 2006-69993 A    Patent Document 13: JP 2005-225841 A    Patent Document 14: JP 2003-306436 A    Patent Document 15: JP 2003-253262 A    Patent Document 16: JP 2003-252770 A    Patent Document 17: JP 2003-95963 A